Using the LD50 for a carcinogen is inappropriate. LD50s are used as a measure of acute toxicity. The issue isn't that it's going to kill you from toxicity, it's

Using the LD50 for a carcinogen is inappropriate. LD50s are used as a measure of acute toxicity. The issue isn't that it's going to kill you from toxicity, it's that if you expose thousands of children to even low levels of it many more of them will get cancers than they otherwise would.